Apparatus for placing rollers in contact in a pressure fuser assembly

ABSTRACT

A cam assembly is mounted on an electrostatographic machine in contact with a structure bar of a pressure roller assembly. Upon activation of a motor, the cam shaft is caused to rotate through a suitable gearing arrangement thereby swinging the assembly about an axis to place the pressure roller in contact with the fuser roller. Upon reaching the end stop position, a solenoid is activated to lock by appropriate linkage the rollers in operational position. Upon deactivation of the solenoid the cam shaft is caused to rotate to its standby position by a torsional spring affixed to the shaft and to the support assembly.

[ Aug. 28, 1973 United States Patent Braun Tregay et 6/1969Stryjewski...........................

[541 APPARATUS FOR PLACING ROLLERS IN 3,398,259 8/1968 CONTACT IN APRESSURE FUSER 3.4521181 ASSEMBLY [75] Inventor:

einer a m .m h C A d r a n r e .B om M o "a ma R J r ma m. J mew m 1 mnil PA Oskar Braun, Williamson, N. Y. Assignee: Xerox Corporation,Stamford, Conn.

22 Filed:

and Louis E. Marn et a1.

[57 ABSTRACT A cam assembly is mounted on an electrostatographic 1machine in contact with a structure bar of a pressure roller assembly.Upon activation of a motor, the cam Dec. 30, 1971 [21] App]. No.:214,304

shaft is caused to rotate through a suitable gearing arrangement therebyswinging the assembly about an axis to place the pressure roller incontact with the fuser [51] Int. Cl.

1105b 3/10, 603g 15/20 [58] Field of Search 355/3; 219/216, 388,

2|9/469; 263/6 34/1 10, 1 1 17/21 roller. Upon reaching the end stopposition, a solenoid is activated to lock by appropriate linkage therollers in operational position. Upon deactivation of the solenoid thecam shaft is caused to rotate to its standby position by a torsionalspring affixed to the shaft and to the support assembly.

3,449,548 Adamek et a1. 219/388 x 3,211,074 Heiart et 219/216 7 Claims,4 Drawing Figures Patented Aug. 28, 1973 2 Sheets-Sheet l Patenfed Aug.28 1973.

i 2 Sheets-Sheet '2 BACKGNOUNI) OF THE INVENTION This invention relatesto electrostatography, and more'particularly to apparatus for placing afuser roller and a pressure roller in contact in an electrostatographicapparatus. I

In the practice of xerography as described in US. Pat No. 2,297,6 9l toChester F. Carlson, a xerographic surface comprising a layer ofphotoconductive insulat-' ing material affixed-to a conductive backingis used to support electrostatic/images. In the usual method of carryingout the process, the xerographic plate is electrostaically chargeduniformly over its surface and then exposed to a light pattern of theimage being-reproduced to thereby discharge the charge in the areaswhere light strikes'the layer; The undisch'arged areas of the layer thusform an electrostatic charge pattern in conformity with theconfiguration of the original light pattern.

The latent electrostatic image may then be developed by contacting itwith a finely divided electrostatically attractable material, such as aresinous powder. The

powder isheld "in the image areas by the electrostatic fields on thelayer; Where the field is greatest, the greatest amount'of material isdeposited; and where the field is'least, little orno material isdeposited. Thus, a powderimage is'produced in conformity with the lightimage of the copy being reproduced. The powder is subsequentlytransferred "to a sheet of paper or other surface and suitably affixed,such as by heat, pressure, andth'e like,'to thereby form a. permanentprint.

The toner may be fixed passing the sheet of paper or other surfaceincluding the transferred'image be- SUMMARY OF THE INVENTION These andother objects of the invention'are obtained by providing a fuserassembly including a fuser roller, a pressure roller mounting assembly,and a cam assembly operatively associated with the pressure rollerassembly. The pressure roller mounting assembly is pivotally mounted tothe frame assembly above the fuser roller mounted for rotation therein.Activation of the cam assembly causes the pressure roller mountingassembly to move downwardly to place the pressure roller in contactwiththe fuser roller. At the termination of the loading cycle, the camassembly is locked in place. Upon release of the locking'means, theforce of torsion'springs and the inertia of the cam causes the cam shaftto rotate thereby pennitting the pressure roller to move away from thefuser roller.

DESCRIPTION OF THE DRAWINGS A better understanding of the presentinvention as well as other objects and further features thereof willtween a heated roller and a second roller in pressure OBJECTS OF THEINVENTION An object of this invention is to provide a novel fuserassembly for an electrostatographic machine.

' Another object of thisinverition is to'provide a novel apparatusforplacing the fuser and pressure rollers in contact for an imagetransfer mode of an electrostatographic machine. I

Still another object of the invention is to provide a novel apparatusfor ensuring uniform pressure between the fuser and'pressure rollers ofan electrostatographic machine.

A still further object of the invention is to provide a novelcam loadingassembly for placing the fuser and pressure rollers in contact for animage transfer mode of' an electrostatographic machine and forseparating such'rollers for other modes thereof, e.g when the machine isin a standby mode.

become apparent upon consideration of the following detailed disclosurethereof, especially when taken with the accompanying drawings, whereinlike numerals designate like parts throughout.

FIG. 1 is a schematic sectional view of an electrostatic reproductionmachine embodying the principles of the invention;

FIG. 2 is a side view of the pressure roller assembly 'illustratingthepositioningof the pressure roller in an image transfer mode;

FIG. 3 is a partial sectional isometric view of the fuser assembly; and

FIG. 4 is an enlarge exploded isometric view of the duce image rayscorresponding to the informational ar-' eas. The image rays areprojected by means of an optical system onto the photosensitive surfaceof a xerographicplate in the form of aflexible photoconductive belt 12arranged'on a belt assembly, generally indicated by the referencenumeral 14,

'- The belt 12 comprises a photoconductive layer of selenium whichis'the light receiving surface and imaging medium for the apparatus, ona conductive backing. The surface of the photoconductive belt is madephotosensitiveby a-previous step of uniformly charging the same by meansof a corona generating device or corotron 13.

The belt is joumaled for continuous movement upon three rollers 20, 21and 22 positioned with their axes in parallel. The photoconductive beltassembly 14 is slidably mounted upon two support shafts 23 and 24 withthe roller 22 rotatably supported on the shaft 23 which is secured tothe frame of the apparatus and is rotatably driven by a suitable motorand drive assembly (not shown.) in the direction of the arrow at aconstant rate. During exposure of the belt 12, the portion exposed isthat portion of the belt running between rollers trostatic imagepasses'through a developing station B in than one may be employed) isaffixed to the cam shaft 63 and to the frame 48 to assist in theseparation of the rollers at the termination of an image transfer mode.

In operation upon activation of the machine such as by the depression ofa button by the operator, the element 36 is energized and heats thefuser roller 30 to an which there is positioned a developer assemblygenerally indicated by the reference numeral 15, and which providesdevelopment of the electrostatic image by means of multiple brushes 16as the same moves through the development zone.

The developed electrostatic image is transported by the belt to atransfer station C whereat a sheet of copy paper is moved between atransfer roller and the belt operational temperature range, at whichtime the machine shifts into a standby mode ready to be placed in animage transfer mode. Generation of a signal to place the machine inproduction energizes a clutch in a drive means, generally indicated as90, to drive gear 66 which rotates gear 64 thereby causing the cam shaft63 including cams 62 to rotate clockwise (as shown by the at a speed insynchronism with the moving belt in order to accomplish transfer of thedeveloped image solely by an electrical bias on the transfer roller.There is provided at this station a sheet transport mechanism generallyindicated at 17 adapted to transport sheets of paper from a paperhandling mechanism generally indicated by the reference numeral 18 todeveloped image on the support therefor may be found in the copendingApplication Ser. No. 102,312 assigned to the same assignee.

Referring now to FIGS. 2 and 3, the fuser assembly 19 of this inventionis comprised of a fuser roller 30 and a pressure roller assembly,generally indicated as 32, including a pressure roller 34. The fuserroller 30 is formed of a suitable heat conductive material, such ascopper and is provided with a source of heat 36, such as a quartz lamp,centrally positioned therein to heat the roller 30 to operationaltemperatures. The pressure roller 32 is mounted for rotation in endplates 38..A support bar 40 and a cam follower shaft 42 includingsuitable bearing means 44, are mounted to end plates 38. A pivot shaft46 is affixed to and extends through the end plate 38 and is mounted forrotation in fuser frame assembly,,generally indicated as 48. a

The cam assembly, referring now to FIG. 4, generally indicated as 60,includes cams 62 mounted on a cam shaft 63, one end of which extendsthrough the frame 48 and is provided with a gear 64 having an internallyformed cammed surface 65. The gear 64 engages a drive gear 66, as morefully hereinafter described. A

small cam 66 is positioned on the shaft in juxtaposition to a switchassembly, generally indicated as 68 including two switches. A linkinglatch 70 including a latching surface 72 is mounted for rotation to theframe 48, such as by screw 74 in a manner to contact the latchingsurface 72 at the termination of the loading cycle. One end of a spring76 is affixed to the linking latch 70 with the other end affixed to theframe 48. A lever 80 is positioned below the linking latch 70 and ismounted for rotation to the frame 48 such as by screw 82. One end of thelever 80 is engage by a plunger 84 of a solenoid, generally indicated as86. A torsion spring 88 (more arrow) simultaneously winding torsionspring 88. Upon rotation through a predetermined angle, the cam 66actuates the switch assembly 68, one switch therein deenergizes theclutch in the drive mechanism while the other switch energizes solenoid86. Activation of the solenoid 86 causes the plunger 84 thereof to moveupwardly thereby lifting lever 80 which raises latching link to a pointwhere the latching surface 72 engages the surface 65 of the gear 64thereby locking the cam shaft63 in the image-fusing mode, i.e., thecounterclockwise movement of the cam shaft 63 is. prevented. Thepressure roller assembly thus moves from the position of thestandbymode, illustrated by the dotted lines in FIG. 2, to the operationalposition illustrated by the solid lines therein. l

Upon generation of a signal indicative of the completion of the vimagefusing mode, the solenoid is deenergized to permit thetensioningpressure of spring 76 to move the latching surface 72 downwardly awayfrom the cammed surface 65 thereby permitting'the cam shaft 63 to rotatecounterclockwise by the force of spring 88 and naturalinertia of thecams to return the pressure roller to'its position in the standby modeof the machine. 1 a k 1 While the operation of the fuser assembly hasbeen described with reference to the unloading-of the'pressure roller inresponse toa signal (e.g., developed in response to a signal. that theproduction run is completed), it is understood that unloading may alsobe effected automatically in response to a signal generated by othermeans, e.g., overheating of the heating ele-.

ment in the fuser roller 30, paper jams, etc.

While the instant invention as to its objects and advantages has beendescribed herein as carried in specific embodiments thereof, it is notdesired to be lim-' ited thereby; but it is intended to cover theinvention broadly within the scope .of the appended claims.

' What is claimed is: I

f l. A fuser roller assembly'for an electrostatographic machineincluding a fuser roller and a pressure roller, which comprises; i

a. a pressure roller assembly in which said pressure roller is mountedfor rotation, said pressure roller assembly being pivotally mounted injuxtaposition to said fuser roller within said machine and provided withcam following surface means;

' b. acam assembly including cam means disposed in said machine withsaid cam means thereof contacting said cam following surface means c.drive means for rotating said cam assembly to cause said pressure rollerassembly to move towards said fuser roller to a point where saidpressure roller contacts said fuser roller in an image 1 transfer modeof said machine;

d. spring means for moving said pressure roller assembly away from saidfuser roller, said drive means being adapted to place said spring meansunder torsional pressure during rotation of said cam means to said imagetransfer mode; and

e. locking means cooperable with said cam assembly after rotation ofsaid cam assembly and said spring means through a predetermined angle toprevent counter rotation of said cam assembly and moving of saidpressure roller assembly away from said fuser roller by said springmeans.

2. The apparatus as defined in claim 1 wherein said locking means isengaged by movement of a solenoid means.

3. The apparatus as defined in claim 2 wherein said electrostatographicmachine has means to provide a signal following said image transfermode,

and means to deactivate said solenoid means and disengage said lockingmeans in response to said signal.

4. The apparatus as defined in claim 2 wherein said solenoid means isactivated by a switch activated by a cam means mounted on a shaft ofsaid cam assembly.

5. The apparatus as defined in claim 1 wherein said drive'means isdeactivated by a switch activated by a cam meansmounted on a shaft ofsaid cam assembly.

6. The apparatus as defined in claim 1 wherein said electrostatographicmachine has means to provide a signal responsive to said image transfermode;

and means for activating said drive means in response to said signal.

7. in the fusing apparatus adapted for use with copy producing machinesof the type comprising a roller pair in pressure relationship, with atleast one of said rollers being heated, the combination of:

means supporting said rollers for movement relative to one another in toand out of pressure relationship;

drive means adapted when actuated to move said rollers into pressurerelationship;

bias means adapted when loaded and activated to move said rollers apart,said drive means serving when actuated to load said bias means inpreparation for subsequent release of said rollers;

means for locking said rollers in pressure relationship with said biasmeans in a preset loaded condition, ready to move said rollers apart;and

means to release said locking means and activate said bias means wherebysaid bias means moves said rollers apart. I

1. A fuser roller assembly for an electrostatographic machine includinga fuser roller and a pressure roller, which comprises; a. a pressureroller assembly in which said pressure roller is mounted for rotation,said pressure roller assembly being pivotally mounted in juxtapositionto said fuser roller within said machine and provided with cam followingsurface means; b. a cam assembly including cam means disposed in saidmachine with said cam means thereof contacting said cam followingsurface means c. drive means for rotating said cam assembly to causesaid pressure roller assembly to move towards said fuser roller to apoint where said pressure roller contacts said fuser roller in an imagetransfer mode of said machine; d. spring means for moving said pressureroller assembly away from said fuser roller, said drive means beingadapted to place said spring means under torsional pressure duringrotation of said cam means to said image transfer mode; and e. lockingmeans cooperable with said cam assembly after rotation of said camassembly and said spring means through a predetermined angle to preventcounter rotation of said cam assembly and moving of said pressure rollerassembly away from said fuser roller by said spring means.
 2. Theapparatus as defined in claim 1 wherein said locking means is engaged bymovement of a solenoid means.
 3. The apparatus as defined in claim 2wherein said electrostatographic machine has means to provide a signalfollowing said image transfer mode, and means to deactivate saidsolenoid means and disengage said locking means in response to saidsignal.
 4. The apparatus as defined in claim 2 wherein said solenoidmeans is activated by a switch activated by a cam means mounted on ashaft of said cam assembly.
 5. The apparatus as defined in claim 1wherein said drive means is deactivated by a switch activated by a cammeans mounted on a shaft of said cam assembly.
 6. The apparatus asdefined in claim 1 wherein said electrostatographic machine has means toprovide a signal responsive to said image transfer mode; and means foractivating said drive means in response to said signal.
 7. In the fusingapparatus adapted for use with copy producing machines of the typecomprising a rOller pair in pressure relationship, with at least one ofsaid rollers being heated, the combination of: means supporting saidrollers for movement relative to one another in to and out of pressurerelationship; drive means adapted when actuated to move said rollersinto pressure relationship; bias means adapted when loaded and activatedto move said rollers apart, said drive means serving when actuated toload said bias means in preparation for subsequent release of saidrollers; means for locking said rollers in pressure relationship withsaid bias means in a preset loaded condition, ready to move said rollersapart; and means to release said locking means and activate said biasmeans whereby said bias means moves said rollers apart.